A quality assurance program for an HMO has been proposed which is based on measurement of three dimensions of the quality of medical care. Periodically, the accessibility of the HMO to members' requests for medical care, the effectiveness of care rendered, and the efficiency of the system in delivering care will be measured. The approach is population based because it incorporates measurement of the quality of care for all enrolled members, not only those who use services. The overall objective is to measure these parameters of the quality of care, to use them to ascertain difficulties in the delivery system and to suggesd changes, and to design educational program to improve the care being given. Accessibility will be measured for users of services in terms of the patient effort expanded to obtain those services. The accessibility index is based on the number of contacts and the length of time required to obtain care. For non-users of services, accessibility will be determined by measurement of their perception of the accessibility of the system. Effectiveness will be determined for most problems by the change in patient perceived problem status over tme, and also by process of care review and biologic outcome studies whre indicated. Efficiency will be calculated by using the unit cost data (available through the Columbia Medical Plan's management information system) applied to utilization data per problem managed, and by relating this cost data to the effectiveness of care. An EMCRO Committee, which will be responsible for quality assurance, will be representative of the providers of care, the administrators of the Plan, and the recipients of care, and will direct the EMCRO operation. As part of the research effort, this method of quality assessment will be evaluated in terms of its validity and usefulness in uncovering deficiencies in the delivery system. The costs and benefits of this program, in relation to changes which improve accessibility, effectiveness, and efficiency of care, will be determined.